Nest-Site Selection in Barn Swallows (Hirundo rustica): Patterns Consistent With the Human Proximity Hypothesis...

Nest-site selection is critical to avian reproductive success. Although human activity is known to influence nest-site choice in birds, whether humans facilitate or impede avian reproduction remains a matter of debate. The human proximity hypothesis proposes that birds breeding near human habitation experience reduced rates of nest predation and brood parasitism. To test this hypothesis, we investigated nest-site selection in barn swallows (Hirundo rustica) across three provinces in China: Hainan, Guizhou, and Heilongjiang. Occupancy rates of the breeding swallow nests were 34.6% in inhabited buildings but fell sharply to 0.9% in uninhabited buildings. Among all active nests recorded, 98.1% were located in inhabited buildings, and swallows showed a strong preference for old buildings (91.9%). Outdoor nests (75.1%) significantly outnumbered indoor nests (24.9%), and outdoor nests were placed at significantly greater heights than indoor nests. Our findings are consistent with the human proximity hypothesis, suggesting that barn swallows maintain close associations with humans and may benefit from reduced predation and parasitism risk associated with human proximity.